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107 lines
3.1 KiB
C++
107 lines
3.1 KiB
C++
#include "focal_estimators.hpp"
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#include "util.hpp"
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using namespace std;
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using namespace cv;
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void focalsFromHomography(const Mat& H, double &f0, double &f1, bool &f0_ok, bool &f1_ok)
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{
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CV_Assert(H.type() == CV_64F && H.size() == Size(3, 3));
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const double h[9] =
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{
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H.at<double>(0, 0), H.at<double>(0, 1), H.at<double>(0, 2),
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H.at<double>(1, 0), H.at<double>(1, 1), H.at<double>(1, 2),
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H.at<double>(2, 0), H.at<double>(2, 1), H.at<double>(2, 2)
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};
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f1_ok = true;
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double denom1 = h[6] * h[7];
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double denom2 = (h[7] - h[6]) * (h[7] + h[6]);
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if (max(abs(denom1), abs(denom2)) < 1e-5)
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f1_ok = false;
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else
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{
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double val1 = -(h[0] * h[1] + h[3] * h[4]) / denom1;
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double val2 = (h[0] * h[0] + h[3] * h[3] - h[1] * h[1] - h[4] * h[4]) / denom2;
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if (val1 < val2)
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swap(val1, val2);
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if (val1 > 0 && val2 > 0)
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f1 = sqrt(abs(denom1) > abs(denom2) ? val1 : val2);
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else if (val1 > 0)
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f1 = sqrt(val1);
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else
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f1_ok = false;
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}
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f0_ok = true;
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denom1 = h[0] * h[3] + h[1] * h[4];
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denom2 = h[0] * h[0] + h[1] * h[1] - h[3] * h[3] - h[4] * h[4];
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if (max(abs(denom1), abs(denom2)) < 1e-5)
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f0_ok = false;
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else
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{
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double val1 = -h[2] * h[5] / denom1;
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double val2 = (h[5] * h[5] - h[2] * h[2]) / denom2;
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if (val1 < val2)
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swap(val1, val2);
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if (val1 > 0 && val2 > 0)
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f0 = sqrt(abs(denom1) > abs(denom2) ? val1 : val2);
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else if (val1 > 0)
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f0 = sqrt(val1);
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else
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f0_ok = false;
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}
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}
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bool focalsFromFundamental(const Mat &F, double &f0, double &f1)
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{
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CV_Assert(F.type() == CV_64F);
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CV_Assert(F.size() == Size(3, 3));
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Mat Ft = F.t();
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Mat k = Mat::zeros(3, 1, CV_64F);
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k.at<double>(2, 0) = 1.f;
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// 1. Compute quantities
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double a = normL2sq(F*Ft*k) / normL2sq(Ft*k);
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double b = normL2sq(Ft*F*k) / normL2sq(F*k);
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double c = sqr(k.dot(F*k)) / (normL2sq(Ft*k) * normL2sq(F*k));
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double d = k.dot(F*Ft*F*k) / k.dot(F*k);
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double A = 1/c + a - 2*d;
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double B = 1/c + b - 2*d;
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double P = 2*(1/c - 2*d + 0.5*normL2sq(F));
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double Q = -(A + B)/c + 0.5*(normL2sq(F*Ft) - 0.5*sqr(normL2sq(F)));
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// 2. Solve quadratic equation Z*Z*a_ + Z*b_ + c_ = 0
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double a_ = 1 + c*P;
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double b_ = -(c*P*P + 2*P + 4*c*Q);
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double c_ = P*P + 4*c*P*Q + 12*A*B;
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double D = b_*b_ - 4*a_*c_;
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if (abs(D) < 1e-5)
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D = 0;
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else if (D < 0)
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return false;
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double D_sqrt = sqrt(D);
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double Z0 = (-b_ - D_sqrt) / (2*a_);
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double Z1 = (-b_ + D_sqrt) / (2*a_);
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// 3. Choose solution
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double w0 = abs(Z0*Z0*Z0 - 3*P*Z0*Z0 + 2*(P*P + 2*Q)*Z0 - 4*(P*Q + 4*A*B/c));
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double w1 = abs(Z1*Z1*Z1 - 3*P*Z1*Z1 + 2*(P*P + 2*Q)*Z1 - 4*(P*Q + 4*A*B/c));
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double Z = Z0;
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if (w1 < w0)
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Z = Z1;
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// 4.
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double X = -1/c*(1 + 2*B/(Z - P));
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double Y = -1/c*(1 + 2*A/(Z - P));
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// 5. Compute focal lengths
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f0 = 1/sqrt(1 + X/normL2sq(Ft*k));
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f1 = 1/sqrt(1 + Y/normL2sq(F*k));
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return true;
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}
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